Sea Bug - A small creature from the trench that was eaten by a tentacle while hiding in the skull in The SpongeBob SquarePants Movie.

The Skeleton Fish - Dies of unknown causes prior to "One Krabs Trash" and resurrected as zombies in the cemetery. Mr. Krabs kills them again by beating/dismembering them a swordfish's nose bone.

Squidward's Hopes and Dreams - Probably died after SpongeBob moved in.

Eugene H. Krabs* - Has died several times throughout the series. In "Born Again Krabs," he dies from food poisoning. The Flying Dutchman revives him. In "Wishing You Well," he gets steamed and eaten alive. However, this death was also not permanent as he appears in many episodes afterwards.

Band Members - Died while trying to play Patrick's song in "Sing a Song of Patrick" because the first guitarist said that they'll do it even if it kills them, so they died because Patrick's song was so horrible.

Chip* - Eaten by Gary in "I Had an Accident." (This might not count as a deceased character, as Chip was never alive in the first place.)

Scooter dies in the episode "Bubble Buddy." However, he appears in later episodes.

Flag Twirlers (Fred and Pilar) - Both were twirling hard by Squidward's commands, and they flew into the sky and hit a helium dirigible. They both died while one of the trumpeters plays Taps, and Squidward lied on the ground. However, one Flag Twirler (Fred) is back near the end of the episode, "Band Geeks."

Scooter - Left buried by "Bubble Buddy" and supposedly drowned from high tide and turned to his angelic soul form. Oddly, he has re-appeared multiple times.

Corporal Sterling - Was shoved in a locker as a prank when Mr. Krabs was in the Navy. Either died from being squashed, hunger, thirst, suffocation or was eaten by the spiders in the locker in "Squidward in Clarinetland."

Mrs. Krabs* - The viewers of SpongeBob have mysteries on what happened to Pearl's mother, Mr. Krabs' wife, Mrs. Krabs. She has never been seen before, and is unknown if she is a sperm whale or not, and if she is dead or divorced from Mr. Krabs.

Ernest Borgnine - Died on July 8, 2012. He played Mermaid Man. Joe Whyte, who had previously played the character in some video games, will be the voice of the new Mermaid Man, since Borgnine passed away.